User`s guide

Overview of Spanning Tree Protocols
5-6 Configuring Spanning Trees
Variousoptionsmaybeconfiguredonaper‐MSTIbasistoallowfordifferingtopologiesbetween
MSTIs.ToreducenetworkcomplexityandprocessingpowerneededtomaintainMSTIs,you
shouldonlycreateasmanyMSTIsasneeded.
Figure 5-2 MSTI 1 in a Region
Figure 5-3 MSTI 2 in the Same Region
Figure 5‐4shows3regionswithfiveMSTIs.Table 5‐2definesthecha r acteristics
ofeachMSTI.
PortsconnectedtoPCsfromDevices1,3,9,and11willbeautomaticallydetectedasedgeports.
Devices4and10aretheCISTregionalrootsand,becausetheycontainthemasterportfortheir
regions,arealsotheregionalrootdevices.EachMSTIcanbeconfigured
toforwardandblock
variousVLANs.
12
34
5
MSTI 1
MST CIST
Regional Root
MSTI 1 Regional Root
Physical Link
Legend:
Blocked VLANs
CIST Root
12
34
5
MSTI 2
MST CIST
Regional Root
MSTI 2
Regional
Root
Physical Link
Legend:
Blocked VLANs